The invention concerns a mechanism to produce filled, sealed tubular bag packages from a filled tube whereby the filled tube is constricted to form the ends of two sequential tubular bag packages, and the constricted area of the tube is sealed by two surrounding, separated bent wire closures whereby two groups of constricting plates may be pressed from both sides against the area of the tube to be constricted, and whereby devices to cut and bend the wire used as bent wire closures, and a transport mechanism for the U-shaped bent wire closures used to seal the constricted area, are provided, whereby the cutting and bending mechanisms each feature a bending stamp and a cutting block outside on the constricting plates of one group and fixed counterpieces, and are driven with the constricting plates, and whereby the transport mechanism is arranged between the constricting plates of one group and is formed by one of the rods running in the groove, distinguished by the facts that the constricting plates together with the cutting and bending mechanisms may be driven by a common drive shaft via cam disks rotating around the common drive shaft, and that two bi-directionally operating cam disks are provided for each group of constricting plates, and one additional bi-directionally operating cam disk is provided for the transport mechanism.
The European Patent No. EP 0 685 397 C1 contains a description of a mechanism intended to produce filled, sealed tubular bag packages from a filled tube in which the drive for individual moving parts of the mechanism is provided by various pneumatic cylinders. This drive mode has enjoyed wide acceptance, but is not well suited for high output, e.g., more than 45 cycles per minute. Additionally, it is characterized by high energy consumption and sound levels.
The published German Patent Application No. DE-AS 11 40 851 published the principle of providing drive for the mechanism""s moving parts by means of linear moveable cam templates. This, however, results in the problem that the movement must be symmetrical to the axis of the tubular bag package so that the tube is not displaced. The published design requires a double drive that must be synchronized. This causes the mechanism to be large and expensive.
A mechanism for the packaging of sausage for which the parts necessary to seal the sausages are driven by rotating cam disks is known from the published German Patent Application No. DE-AS 11 01 997. The design is also rather expensive, however, since a large quantity of components is required to support and drive the cam disks.
The German Patent No. DE 36 10 010 C2 describes a mechanism intended to divide tubular shells in which the moving parts are also driven by rotating cam disks. This design is characterized by high manufacturing expense since the cam disks must act in two directions.
The German Patent No. DE 296 13 336 U1 features a mechanism intended to seal tubular bags for which cam disks are used from one side to move the clamping tools. The tubular bags are separated before clamping by means of a constricting plate operated by a lever mechanism that may be rotated. This design also requires many parts that move in various manners, and is therefore expensive.
Further, the known mechanisms feature difficulties during the sealing of tubular bags with a simple bent wire closure that is placed around the end of the constricted bag since the tubular bag material may slip out of the clamp.
The principal object of this invention is to provide a mechanism, of the type described above that avoids these disadvantages, and particularly which allows higher output.
This object as well as other objects and advantages which will become apparent from the discussion that follows, are achieved by the invention in that the constricting plates and that the bending and cutting mechanisms are driven by a common drive shaft via cam disks, and that two bi-directionally operating cam disks are provided for each group of constricting plates, and one bi-directionally operating cam disk is additionally provided for the transport mechanism.
The mechanism with central cam disk drive based on the invention allows a synchronous procedure without stop times. During this procedure, individual functions are coordinated for mutual compatibility so that they may be performed in series or parallel without stop times. The overall time from the production of the bent wire closure to the completed, sealed package is thereby shortened, allowing the desired increased output rate.
Significant improvements achievable by this invention include:
Priceworthy manufacture of the mechanism;
Reduced energy consumption and thereby reduced operating costs;
Simple construction and low maintenance;
Simple, easy disassembly and reduced cleaning expense, which is of particular advantage when daily cleaning is required; and
High level of functional and operational safety.
A mechanism based on this invention can perform the following functions:
Measured extraction of the bent wire closure wire from a supply roll and insertion into a cutting station;
Cutting the closure wire;
Shaping the bent wire closure;
Transporting the bent wire closure;
Constricting the tubing material so that the product packaged in the tubular bag package is excluded from the clamping area;
Affixing and securing the bent wire closure;
Rolling the bent wire closures, i.e., sealing the constricted area with two clamps, one at the end of the finished package and one at the beginning of the next package; and
Cutting, i.e., separating the packages by cutting between the two closed bent wire closures.
A mechanism based on this invention may be so constructed that all movements are passed radially and parallel to the functional elements via pushrods, thus saving space.
This elaboration also preferably provides, as shown in the aforementioned European Patent No. EP 0 685 397, that the completed bent wire closures be pushed from the cutting and bending mechanism through openings in the external constricting plates by plungers driven by rocker arms and additional cam disks.
A cutting mechanism intended to separate the tubular bag packages also requires a drive in the direction of the constricting plates positioned opposing it, but offset in time from it. An additional cam disk for this drive may be avoided by the advantages of the mechanism in accordance with the invention by the fact that at least one of the cam disks provided for the group of external constricting plates features an additional cam lobe used to operate the cutting mechanism.
Movements of the cam disks and the functional elements of the mechanism based on the invention are a closed system, i.e., they are balanced and adjusted with respect to one another so that no oscillations or vibrations are passed to the support to which the mechanism based on the invention is attached.
Another advantageous embodiment of the invention includes the fact that the wire advancing mechanism may be driven by a chain drive connected with the common drive shaft, and two clamping mechanisms may be provided which open alternately, whereby one of the clamping mechanisms may be moved by a cam disk back and forth in the direction of wire travel. This establishes an advantageous drive for the wire being moved perpendicular to the overall movement direction that is synchronous with the other motions of the mechanism based on the invention.
A compact and space-saving design is achieved by another advantageous embodiment of the invention by including two extended strips in the direction of constricting plate motion, as described in the European Patent No. EP 0 685 397. The ends of these strips are connected to a frame, and act for most of their length as guides for supporting blocks that hold the constricting plates, and which also feature a support for the common drive shaft whereby the strips preferably are provided with slots for the wire cutting and bending mechanisms.
The mechanism based on the invention is preferably so configured that one rotation of the common drive shaft provides one cycle of the constricting plates, transport and closing of the bent wire closures, and separation of the tubular bag packages.
The mechanism based on the invention preferably features a continually adjustable rotational speed of the common drive shaft particularly in order to provide synchronization of the pre- and post-function devices.
A preferred embodiment of the invention is envisioned whereby the cam disks are so shaped that that the time during which the constricting plates are open exceeds the time for which they are closed. This offers the possibility of integrating the time required to fill the bag, during which the filled bag is fed between the opened constricting plates into the overall procedure of the sealing mechanism without interrupting the continuous operation of the sealing mechanism. In this manner, the sealing mechanism may operate in a continuous, energy-saving manner. Thus, it would no longer be necessary that the portioning mechanism positioned before the sealing mechanism operate in sequence with the sealing mechanism, that is, the sealing mechanism might begin to operate after the portioning procedure.
Using the mechanism based on the invention, filled tubular bags are preferably sealed in such a manner that the filling material is forced out of the constricted area of an already filled bag by the constricting plates, producing an air-free filling. This is possible for almost all filling products such as foodstuffs, or other highly viscous products such as caulking material, which are smooth, slippery, and viscous, and which do not contain high-friction components.
This is not possible for filling materials such as mortar which feature corundum, quartz sand, glass, silica, or other high-friction components, since these granular components would only partially slide out of the constricted area during constriction of the filled tube, leaving a remainder clamped in the folds of the constricted tube, thereby perforating the tube during the constricting or sealing procedure. The tubular bag package would therefore leak in this area, allowing at least the less-viscous components of the filling to escape. In order to prevent these disadvantages, existing filling devices leave the closure area free of filled material, which means that the tubular bag package is not completely filled.
In order to prevent these disadvantages and to ensure that even bags containing granular materials are completely filled and are capable of being sealed with bent wire closures, a further embodiment of the invention might feature displacement along the longitudinal direction, in contrast to tubular bag packages fed from above, and cam disks shaped so that the constriction begins above the fill height, is continued during lowering of the mechanism, and the seal is completed using bent wire closures when the constriction has reached the fill height.
Such a further improvement has the advantage that the tubular bag packages can be completely filled with granular material without damaging the shell material. During lowering of the mechanism, the area to be constricted is already partially constricted, but the air still located above the filling material may be forced out of the tubular bag package. Only then would the constrictors close completely and the bent wire closure be affixed. The movement required by this improved embodiment of the invention is shown in FIG. 1 designated with a double arrow.
The mechanism based on the invention creates bent wire closures automatically from continuous wire, i.e., the wire is inserted a predetermined distance into the cutting station where it is cut. Damaged, dull, or poorly-adjusted cutting knives allow the danger that the contact interface, i.e., the edge of the bent wire closure in contact with the filled portion of the package might not be clean and smooth, but rather sharp and jagged. Since the bent wire closure is pressed tight against the package material when it is rolled shut, damage to the material cannot be excluded.
In order to prevent this hazard, a further development of the mechanism based on this invention might include a notching element to align the wire to its subsequent position at the interface before cutting which is so arranged that the edge of the bent wire closure in contact with the filled portion of the package is provided with a smooth, rounded surface.
A particularly advantageous further development of the mechanism based on this invention includes notching tools integrated into the holding jaws of the wire supply feed mechanism. The holding jaws of the wire supply feed mechanism would thus be equipped with notching tools, and the closing force might be so adjusted that the sealing wire may be pre-shaped at the desired place.
Closed bags sealed with the bent wire closures are often subjected to over-pressure after production, e.g., from pressure induced by stacking on pallets for storage whereby the weight of upper-layer packages is supported by those in the lower layers. Over-pressure may also be caused by thermal post-processing of foodstuff packages, e.g., sausages being preserved (boiling, smoking, etc.). These heating processes may create increased internal pressure. This may lead to release of the bent wire closure and thereby destruction of package integrity, particularly when a slippery or greasy packaging material is involved.
In order to prevent such damage and to achieve a reliable seat for the bent wire closure onto the packaging material, use of bent wire closures featuring a profile on the interior surface is known, e.g., from Austrian Patent No. AT 171 031 or German Patent No. DE 38 11 978 C1.
An advantageous mechanism used to bend and cut the bent wire closures may also be employed in the mechanism based on this invention in that it may employ a stamp to produce a high-friction profile on the contact surface of the sealing wire while it is being shaped. This allows simple production of the high-friction profile, also known as a gripping pattern, without requiring a previous functional step to impress the profile onto the wire, and without allowing the bending process to damage or destroy the profile. Such damage has been prevented according to the German Patent No. DE 38 11 978 C1 by selecting a gripping pattern consisting of comprehensive depressions, since these are not subject to damage under high pressure.
Using a mechanism based on the invention, other profiles could be stamped that are selected for their improved gripping characteristics, particularly gripping profiles featuring raised bumps. Such a mechanism based on the invention could be improved to include arrangement of the bumps in several rows, with the bumps in each row symmetrically offset from each other. For this, the bumps might be lens-shaped, triangular pyramid-shaped, or square pyramid-shaped, and/or the pattern might include a center row of bumps consisting of several bead-shaped bumps arranged along the longitudinal direction of the gripping profile.
For a full understanding of the present invention, reference should now be made to the following detailed description of the preferred embodiments of the invention as illustrated in the accompanying drawings.